Visualizing implanted tumors in mice with magnetic resonance imaging using magnetotactic bacteria

Clin Cancer Res. 2009 Aug 15;15(16):5170-7. doi: 10.1158/1078-0432.CCR-08-3206. Epub 2009 Aug 11.


Purpose: To determine if magnetotactic bacteria can target tumors in mice and provide positive contrast for visualization using magnetic resonance imaging.

Experimental design: The ability of the magnetotactic bacterium, Magnetospirillum magneticum AMB-1 (referred to from here as AMB-1), to confer positive magnetic resonance imaging contrast was determined in vitro and in vivo. For the latter studies, AMB-1 were injected either i.t. or i.v. Bacterial growth conditions were manipulated to produce small (approximately 25-nm diameter) magnetite particles, which were observed using transmission electron microscopy. Tumor targeting was confirmed using 64Cu-labeled bacteria and positron emission tomography and by determination of viable cell counts recovered from different organs and the tumor.

Results: We show that AMB-1 bacteria with small magnetite particles generate T1-weighted positive contrast, enhancing in vivo visualization by magnetic resonance imaging. Following i.v. injection of 64Cu-labeled AMB-1, positron emission tomography imaging revealed increasing colonization of tumors and decreasing infection of organs after 4 hours. Viable cell counts showed that, by day 6, the bacteria had colonized tumors but were cleared completely from other organs. Magnetic resonance imaging showed a 1.22-fold (P = 0.003) increased positive contrast in tumors on day 2 and a 1.39-fold increase (P = 0.0007) on day 6.

Conclusion: Magnetotactic bacteria can produce positive magnetic resonance imaging contrast and colonize mouse tumor xenografts, providing a potential tool for improved magnetic resonance imaging visualization in preclinical and translational studies to track cancer.

Publication types

  • Evaluation Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Bacterial Adhesion / physiology
  • Cells, Cultured
  • Chemotaxis / physiology*
  • Female
  • Ferrosoferric Oxide* / chemistry
  • Ferrosoferric Oxide* / metabolism
  • Magnetic Resonance Imaging / methods*
  • Magnetospirillum / metabolism
  • Magnetospirillum / physiology*
  • Mice
  • Mice, Nude
  • Neoplasm Transplantation
  • Neoplasms / diagnostic imaging*
  • Neoplasms / metabolism
  • Neoplasms / microbiology
  • Radiography
  • Transplantation, Heterologous


  • Ferrosoferric Oxide